400 PHYSIOLOGICAL CHEMISTRY 



acetic ether, and in water. Its solutions show characteristic absorption 

 bands (see Absorption Spectra, Plate II). Under normal conditions 

 urobilin is derived from the bile pigments in the intestine. 



Urobilin is increased in most acute infectious diseases such as ery- 

 sipelas, malaria, pneumonia, and scarlet fever. It is also increased in 

 appendicitis, carcinoma of the liver, catarrhal icterus, pernicious anemia, 

 and in cases of poisoning by antifebrin, antipyrin, pyridin, and potas- 

 sium chlorate. In general it is usually increased when blood destruction 

 is excessive and in disturbances of the liver. It is markedly decreased 

 in phosphorus poisoning. 



In liver disease, of any type, urobilinogen occurs in the urine. Its 

 detection is the basis of a specific test for functional liver incapacity. 



EXPERIMENTS 



1. Ammoniacal-zinc Chloride Test. Render some of the urine ammoniacal 

 by the addition of ammonium hydroxide, and after allowing it to stand a short 

 time filter off the precipitate of phosphates and add a few drops of zinc chloride 

 solution to the filtrate. Observe the production of a greenish fluorescence. 

 Examine the fluid by means of the spectroscope and note the absorption band 

 which occupies much the same position as the absorption band of urobilin in acid 

 solution (see Absorption Spectra, Plate II). 



2. Ether-absolute Alcohol Test. Mix urine and pure ether in equal volumes 

 and shake gently in a separatory funnel. Separate the ether extract, evaporate it 

 to dryness, and dissolve the residue in 2-3 c.c. of absolute alcohol. Note the 

 greenish fluorescence. Examine the solution spectroscopically and observe the 

 characteristic absorption band (see Absorption Spectra, Plate II). 



3. Ring Test. Acidify 25 c.c. of urine with 2-3 drops of concentrated hydro- 

 chloric acid, add 5 c.c. of chloroform and shake the mixture. Separate the chloro- 

 form, place it in a test-tube, and add carefully 3-5 c.c. of an alcoholic solution of 

 zinc acetate. Observe the formation of a green ring at the zone of contact of the 

 two fluids. If the tube is shaken a fluorescence may be observed. 



4. Spectroscopic Examination. Acidify the urine with hydrochloric acid and 

 allow it to remain exposed to the air for a few moments. By this means if any 

 urobilinogen is present it will be transformed into urobilin. The urine may now be 

 examined by means of the spectroscope. If urobilin is present in the fluid the char- 

 acteristic absorption band lying between b and F will be observed (see Absorption 

 Spectra, Plate II). It may be found necessary to dilute the urine with water before 

 a distinct absorption band is observed. This test may be modified by acidifying 

 10 c.c. of urine with hydrochloric acid and shaking it gently with 5 c.c. of amyl 

 alcohol. The alcoholic extract when examined spectroscopically will show the 

 characteristic urobilin absorption band. (Note the spectroscopic examination in 

 experiment (i) above.) 



5. Iodine Test (Gerhardt). To 20 c.c. of urine add 3-5 c.c. of chloroform 

 and shake well. Separate the chloroform extract and add to it a few drops of 

 iodine solution (I in KI). Render the mixture alkaline with dilute solution of 

 potassium hydroxide and note the production of a yellow or yellowish-brown color. 

 The solution ordinarily exhibits a greenish fluorescence. 



